The present invention relates to seals for valves and particularly to seals for a valve having a rotatable valving member which controls flow in a valving chamber between an inlet and an outlet in response to rotation of the valving member. Valves of this type have proven to be generally relatively low in manufacturing costs and particularly suitable for controlling flow of hot water to a passenger compartment heater core in motor vehicles. Heretofore, such heater core valves have been provided with a rotatable butterfly or throttle plate type valving member which has been manually actuated; and, more recently, moved by a servo actuator such as a vacuum motor or electric servo motor. However, butterfly type water valves provide nearly full flow when the butterfly plate is rotated from a closed position to only about one-fourth of its fully open position; and, therefore accurate flow control by the servo actuator is quite difficult to achieve.
With the advent of microcomputer based electronic controllers, it has been desired to provide an all electrical control system for motor vehicle passenger compartment climate control systems. Where the vehicle passenger compartment climate control system utilizes stacked cores, i.e., has the heater core and the passenger compartment air conditioner heat exchanger or evaporator disposed fluidically in series in the blower air discharge plenum, it has become necessary to provide linear response for the valve controlling flow of hot water (engine coolant) to the heater core in order for the system controller to operate the system without executing extremes of heating and cooling to regulate cabin temperature. Thus, it has been desired to provide a heater core valve which provides nearly linear flow or proportional flow control with respect to movement of the valve member. Furthermore, in order to minimize the operating force required to move the valve member, particularly where the valve is to be electrically operated, it has been desired to employ a rotary valve. It has therefore been desired to provide a rotary valving mechanism which provides nearly proportional control of the flow with respect to rotation of the valving member.
It has been proposed to use a barrel or rotary spool type valve which is transversely or cross ported to control the flow between a valve inlet port and a valve outlet port provided in the valving chamber. However, problems have been encountered in designing and manufacturing such a rotary barrel type water valve inasmuch as providing a rotary sliding or face seal about the cross port with respect to the valving chamber has proven extremely difficult and has resulted in a relatively low number of cycles or operations in the service life of a heater core water valve. Tolerances in manufacturing have created a wide variation in the percentage of compression of the seal required to maintain sealing integrity; and, problems of foundry core sand from the engine water jacket passages have caused seal scoring and leakage of the seal. In numerous cases this has resulted in the inability to shut off flow to the passenger department heater core and effectively disabling of the cooling mode of system operation. This has been particularly troublesome where the heater core is fluidically in tandem or series with the air conditioning system refrigerant evaporator coil provided in the forced air plenum of the vehicle passenger compartment climate control system.
Heretofore, known barrel type rotary water valves as shown in FIG. 1 have employed a face seal formed of resilient sealing material such as elastomer having a curved face 1 configured to conform to the surface of the rotary valving member; and, on the opposite or face 2 configured to seal about the rim of one of the valve port. A tubular extension 3 is provided from the inner periphery of the seal, which extension inserted into the valve port 4 in the valve body 5 for locating the seal thereabout. This arrangement has proven to be relatively costly in manufacturing the seal and difficult to assemble in mass production for the water valve. Furthermore, the variation in seal dimensions resulting from molding operations for the seal has proven excessive with the result that a widely varying amount of seal compression has occurred in the valves in mass production; and, leakage and sealing problems have resulted.
Thus, it has long been desired to provide a face seal for a rotary valve which is low in manufacturing costs and can accommodate a wide variation of valve port dimensions and provides a consistent and satisfactory amount of compression of the seal during valve assembly without requiring special operations or tooling for valve assembly.
The present invention provides a face seal for a rotary barrel type valve, particularly suitable for controlling flow of hot water to a vehicle passenger compartment heater core. The seal is formed of resiliently compressible material with an arcuate configuration having a concave inner face with a rib formed about the flow passage passing through the seal to the convex outer face. The seal is preferably formed in a rectangular plan form with oppositely disposed spaced parallel edges which have flanges formed thereon which facilitate sliding assembly and retention in a valve body grooved to receive the seals. The rib formed about the flow passage on the inner face of the seal member provides adequate material to ensure a sufficient amount of localized compression of the seal between the rotary valving member and the valve body upon assembly in the valve so as to provide reliable sealing during movement of the valve member and thereby minimizes the occurrence of leakage.